Safety latch

Abstract

A latch suitable for use on the door of a walk-in refrigerator can be opened from the exterior thereof and in addition from the inside of the cabinet as well as by means of an electrical signal. The latch is provided with a vapor barrier to prevent flow of water vapor along that part of the mechanism by means of which the latch is operable from the interior of the cabinet, flow of water vapor presenting the danger of frost-formation in said mechanism which could adversely affect the operation thereof. Optionally, the latch is provided with a switch which is closed on operation of the latch to activate an external device such as a vent port or an alarm signal.

What is claimed is: 
     
       1. An improved latch suitable for use on the door of a walk-in refrigerator cabinet, said latch including a latch mechanism and housing therefor, a retractable bolt in said housing for engaging a striker assembly attached to the jamb of said cabinet, a retractor handle pivotably mounted to said housing for operating said latch mechanism to retract said bolt, said handle being movable between seated position in which said bolt is extended for engaging said striker assembly and a retracted position in which said bolt is retracted from said striker assembly for opening said door, locking means mounted to said housing for selectively preventing retraction of said handle, and a pushrod for passing through a corresponding channel in said door and into an opening in said housing for activating said latch mechanism for retracting said bolt independently of whether said locking means is in locked or unlocked condition, wherein said improvement comprises a vapor barrier disposed for prevention of entry of water vapor between said pushrod and the wall of said channel cabinet and thereby for prevention of frost buildup which could interfere with the operation of said pushrod. 
     
     
       2. The improved latch as defined in claim 1, wherein said vapor barrier includes elements disposed at both the inner and outer surfaces of said door around said pushrod. 
     
     
       3. The improved latch as defined in claim 1, wherein said vapor barrier comprises a sheet of flexible plastic over said pushrod, said plastic sheet being sealingly attachable to the inner surface of said door to exclude water vapor from entering said channel while permitting operation of said pushrod by exertion of manual force through said sheet and against said pushrod. 
     
     
       4. The improved latch as defined in claim 3, wherein said vapor barrier further includes a cup sealingly attached to the periphery of said sheet and disposed for seating in a corresponding recess at the inner surface of said door, said cup having a centrally disposed opening for passage of said pushrod therethrough, said cup constituting an additional vapor barrier element. 
     
     
       5. The improvement as defined in any of claims 1, 2, 3 or 4, further comprising switch means mounted to said latch so that retraction of said bolt closes said switch means, said switch means being connectable to the exterior of said latch for operation of an auxiliary device. 
     
     
       6. The improvement as defined in any of claims 1, 2, 3 or 4, further comprising solenoid means operatively connected to said latch mechanism for retracting said bolt in response to an external electrical signal independently of whether said locking means is in locked or unlocked condition. 
     
     
       7. A latch suitable for releasably holding the door of a walk-in refrigerator cabinet to the corresponding jamb, comprising: a housing;   a handle having a first arm exterior to said housing and a second arm interior to said housing pivotably mounted to said housing at the junction of said arms for rotation between a retracted position and a seated position corresponding to open and closed position of said latch, respectively, said handle having first pin means at the end of said second arm;   retractor bar means having an indentation for receiving said first pin means and connecting said bar means to said handle, said bar means having a longitudinal slot;   yoke pin means mounted to said housing and passing through said slot;   bolt means pivoted to said housing for releasably engaging a striker assembly affixed to said jamb and thereby holding said door to said jamb, and connected with said bar means for being moved by same into and out of engagement with said striker assembly;   spring means disposed for urging said bar means in a direction such as to move said handle into seated position and thereby to move said bolt means into engagement with said striker assembly;   retractor link and cam link connecting said bolt means with said retractor bar means for drawing said bolt means into and out of engagement with said striker assembly when said handle is rotated from and to retracted position;   cam washer means slidably mounted on said retractor bar means for transmitting force from said spring means against said cam link, said cam link having a cam end shaped for rotating said cam link in a first direction under the urging of spring means by way of said cam washer means;   second pin means pivotably joining said bolt means and said retractor link;   third pin means pivotably joining said retractor link and said cam link;   fourth pin means pivotably joining said cam link and said retractor bar;   tab member integral with one of said retractor and cam links and disposed proximate said third pin means for limiting the extent of rotation of said cam link in said first direction under the urging of said first spring means as transmitted toward said bolt means for engaging said striker assembly;   inside release yoke means for retracting said bolt means from within said cabinet independently of whether said latch is locked, said inside release yoke means being movable between a seated position and an active position and including yoke means pivotably supported on said housing and having a yoked arm and an operating arm, said housing having an opening therein providing access to said yoked arm from the exterior of said housing, said operating arm being disposed for engaging said third pin means to move said third pin means and thereby rotate said cam link in the direction opposite to said first direction for thereby drawing said second pin means toward said fourth pin for retracting said bolt means from said striker assembly, said inside release yoke means including pushrod means for passing through a channel in said door, one end of said pushrod being disposed within said opening in said housing for making contact with said yoked arm and for pushing against same, the other end of said pushrod being positionable at the inner face of said door for receiving a manual push from within said cabinet to effect retraction of said bolt means, said third pin means engaging said yoke means for returning same from active position to seated position under urging of said spring means by rotation of said cam link in said first direction, whereby a single spring means can effect the three functions of engaging said bolt means with said striker assembly and returning said handle and yoke means to seated positions.   
     
     
       8. The latch as defined in claim 7, further comprising solenoid means connected to said inside release yoke means for operating same in response to an external electrical signal. 
     
     
       9. The latch as defined in claim 7, further comprising a vapor barrier for sealing said pushrod for axial movement relative to said door while preventing flow of water vapor along the surface of said rod. 
     
     
       10. The latch as defined in claim 9, wherein said vapor barrier comprises a sheet of flexible plastic sealable to an interior surface of said door over the end of said pushrod. 
     
     
       11. The latch as defined in claim 9, wherein said vapor barrier includes a cup member having an opening therethrough for transit of said pushrod therethrough, said cup member being sealed at the rim thereof to said sheet and being arranged and constructed for fitting into a corresponding recess on said door, said cup providing for inward displacement of said sheet and providing a second barrier against transfer of water vapor. 
     
     
       12. The latch as defined in claims 7, 8, 9 or 10, further comprising a vapor barrier at said housing and disposed about said opening for preventing entry of water vapor into said latch through said opening and around said pushrod. 
     
     
       13. The latch as defined in claim 7, wherein said housing has an opening therein for receiving the hasp of a padlock, said opening being so disposed that said hasp prevents movement of said retractor bar in a direction such as to withdraw said bolt from said striker assembly. 
     
     
       14. The latch as defined in claim 7, further comprising supplementary spring means mounted to said latch for urging said inside release yoke means from active position to seated position. 
     
     
       15. The latch as defined in claim 7, wherein said inside release yoke means is pivotably mounted on said yoke pin means and thereby to said housing.